I have a dual monitor, overclocked 3570, with 32GB of ram and SLI GTX 670s and it cost me less than 3 grand and I absolutely splurged needlessly on every component.
What is your brother looking to do with the computer and does he really need a $3000 computer when he likely wont see any difference with a $2000 computer performance wise unless hes running some specific games at multi-monitor resolutions?
For $3 grand, this is more or less my build, which was absolutely overkill for anything. You can save quite a bit of money buy not going for the cosmos 2 and dropping to 16GB ram without affecting anything at all. Hell you could get away with 1 video card too if you're not using multiple monitors.
CPU:Intel Core i5 3570k at 4.2Ghz
CPU Cooler: Phanteks PH-TC14PE
Ram: 32GB DDR3 (IIRC Patriot DDR 1866, though you likely won't see any difference with even 16 or 8 gb unless you need to do large projects with photoshop or premiere pro)
Motherboard: Asus P8Z77-V Pro
GPU: 2x Geforce GTX 670SLI (Do noy buy a Gigabyte Windforce board with the Asus motherboard, it refuses to run at PCI-E 3.0 speeds on the Asus board, learned this the hard way)
SSD : 256GB Crucial M4
Hard Drive: 3TB Seagate Barracuda
PSU: Rosewill Capstone 750-M (Superflower 80+ Gold PSU, outstanding rating by Johnnyguru)
Case: Cooler Master Cosmos 2
Monitors: 2x Dell U2312HM Monitors
Keyboard and Mouse: Corsair K90 and M60 (The K90 takes quite a bit of getting used to for typing, but works great for gaming)
Sound Card: Creative Sound Blaster X-Fi Titanium
Speakers: Logitech Z623 speakers
Headphones: Audio Technica ATH-A700D headphones
Microphone: Clip on mic
Operating System: Win 7 Pro
DVD Drive: Asus DVD +-RW
Looking at the Alienware prices, it seems like it's $300-$800 profit for Alienware depending on the upgrades you're getting.
For bang for the buck, I saved this as a build for a friend a couple weeks ago:
PCPartPicker part list /
Price breakdown by merchant /
Benchmarks
CPU: Intel Core i5-3570K 3.4GHz Quad-Core Processor ($189.99 @ Microcenter)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($29.99 @ Microcenter)
Motherboard: ASRock Z77 Extreme4 ATX LGA1155 Motherboard ($134.99 @ Microcenter)
Memory: G.Skill Ripjaws X Series 16GB (2 x 8GB) DDR3-1600 Memory ($89.99 @ Newegg)
Storage: Samsung Spinpoint F3 1TB 3.5" 7200RPM Internal Hard Drive ($89.99 @ Newegg)
Storage: Crucial M4 256GB 2.5" Solid State Disk ($209.00 @ B&H)
Video Card: Gigabyte GeForce GTX 670 2GB Video Card ($399.98 @ NCIX US)
Case: Corsair 400R ATX Mid Tower Case ($89.99 @ Newegg)
Power Supply: Corsair 600W ATX12V Power Supply ($49.99 @ Newegg)
Optical Drive: Sony AD-7280S-0B DVD/CD Writer ($17.99 @ Amazon)
Operating System: Microsoft Windows 7 Home Premium SP1 (64-bit) ($90.63 @ Amazon)
Total: $1392.53
(Prices include shipping and discounts when available.)
(Generated by PCPartPicker 2012-08-12 21:44 EDT-0400)